Among the most rewarding traits of perennials is the fact that they come up unprompted year after year to offer the garden masses and highlights of color in uninterrupted but ever-changing patterns from April to November.
A perennial, in the broadest horticultural definition, is any plant that lives for three of more years. The definition covers a lot of ground, embracing both dandelions and giant redwoods and thousands of species in between.
But when gardeners talk about perennials, they almost always mean -as does this website- flowering garden plants with stems that are herbaceous, i.e., fleshy rather than woody, and that usually die down to the soil's surface before winter, while the roots remain alive and ready to send up new growth the next season. (Technically, bulbous plants such as tulips and daffodils are perennials, but they generally are classified separately because of their method of storing food for next year's growth.)
Perennials flower abundantly and multiply without being coaxed. Most of them are easy to grow. Some require spadework occasionally, but many will tolerate considerable neglect. In fact, I have seen long abandoned farms in Arkansas where gaping cellar holes and tumbled walls of old houses were adorned with great clumps of day lilies, thriving and spreading; and morning glory rising as always to greet the day.
Here are a list of articles on specific plants you may find of interest....